This invention relates to flying model airplanes, and more specifically, to electrically powered scale model airplanes of the U-control type, that is, of the type which is controlled in circular flight by an operator manipulating a pair of control wires from the center of the circular flight path.
U-control model airplanes and, specifically, gas powered model airplanes, have been manufactured for many years. Typically, these airplanes include an extremely lightweight gasoline powered engine which operates at high RPM and permits scale models to be designed without particular concern that the aircraft will be nose heavy in comparison with the full scale aircraft which is being emulated.
More recently, flying model airplanes using electric motors and rechargeable dry cells have been produced, but attempts to build scale models of full size aircraft using electric motors have typically required long drive shafts between the relatively heavy electric drive motor and the nose mounted propeller in order to shift the center of gravity toward the rear of the aircraft and thus balance the aircraft while in flight. Such long drive shaft arrangements often result in higher model costs, since additional bearings other than the bearings within the motor themselves must be positioned and mounted in the nose of the aircraft. Furthermore, the long drive shaft often requires an extra part to be assembled into the aircraft, since most small high speed motors are designed with a relatively short armature shaft.
Prior art model airplanes of the electrically driven type are usually difficult for one person to operate, since a switch must be closed at the aircraft to start the electric motor and the operator must be positioned at the center of the flight circle to fly the aircraft. A prior attempt at permitting an operator to remotely operate a switch from the circle center is shown in U.S. Pat. No. 3,696,558. In this patent, however, no easy means is provided for setting the switch in the "off" position during battery charging and later closing the switch from the circle center using the normal bellcrank control lines, all while assuring that manipulation of the bellcrank will not later open the switch.
Wiring within model electric airplanes has often been a problem. Since recharging of the chargeable dry cells must be provided from outside of the airplane, a switch must be provided for breaking the circuit between the rechargeable batteries and the motor, and spring contacts must be provided for the rechargeable dry cells. Often, a substantial portion of the cost of producing an electric model airplane can be the assembly of wiring within the airplane to interconnect the various parts thereof. In addition, since the rechargeable cells can be damaged by reverse polarization during charging, elaborate and costly arrangements have been provided in the prior art for assuring proper charging polarity.